Heat-shrinkable milky film, shrink label and container with label

ABSTRACT

A heat-shrinkable opaque white film of this invention includes a core layer, and white back and front layers, the core layer having a chromatic color impervious to light at wavelengths of 380 to 500 nm or an achromatic color. The core layer may contain a black, yellow, red, or brown pigment. The heat-shrinkable opaque white film in a preferred embodiment has a transmission factor to light at wavelengths of 380 to 500 nm of 5% or less. In another preferred embodiment of the heat-shrinkable opaque white film, the core layer has an achromatic color and the film has a transmission factor to light at wavelengths of 200 to 600 nm of 3% or less. A shrink label of this invention has the heat-shrinkable opaque white film, and a preprinted ink label layer arranged on a surface of the front layer of the film. A labeled container of this invention includes a container body and the shrink label arranged on the container body. This labeled container can prevent discoloration and deterioration of contents induced by light, enables clear printing typically of a design and gives excellent visual impression of the contents.

TECHNICAL FIELD

The present invention relates to a heat-shrinkable opaque white(translucent white) film which is impervious to light, a shrink labelprepared from the heat-shrinkable opaque white film, and a labeledcontainer including a container body and the label applied to thecontainer body by heat shrinkage.

BACKGROUND ART

Alcoholic beverages such as beer, sake, and wine, green tea, andbeverages containing vitamins are susceptible to discoloration and/ordeterioration caused by light, in particular light at wavelengths of 380to 500 nm. Widely used containers typically for beverages susceptible tolight-induced deterioration are plastic bottles and glass bottles whichare colored for achieving imperviousness to light. These coloredcontainers contain colorants, and this significantly inhibits recoveryand reuse of used containers.

A proposed solution to this is labeled containers including a colorless,transparent plastic bottle or glass bottle as a container body coatedwith a shrink label having imperviousness to light. Japanese UnexaminedPatent Application Publication (JP-A) No. 2002-68202, for example,discloses a bottle having a heat-shrinkable synthetic resin filmcontaining an ultraviolet screening agent such as zinc oxide. JP-A No.2002-285020 discloses a container with a heat-shrinkable label preparedfrom a white film containing a specific amount of titanium dioxide.These containers, however, have relatively high light transmissionfactor particularly to visible light and do not have sufficientimperviousness to light. JP-A No. 2003-26252 discloses a container witha shrink label. The shrink label includes a heat-shrinkable filmcontaining a white pigment and having one side to be designed and theother side printed black. This type of container, however, has a blackinner side of the label, and when one look in on a beverage such as milkbeverage or beer at an inlet of the container bottle, the beverage looksblackish and has poor appearance which could deteriorate one's appetite.

DISCLOSURE OF INVENTION

Accordingly, an object of the present invention is to provide a labeledcontainer that can prevent its contents from discoloration anddeterioration caused by light, can be printed clearly typically with adesign, and yields an excellent appearance of the contents when viewedfrom outside. Another object of the present invention is to provide aheat-shrinkable opaque white film and a shrink label which are usefulfor preparing the labeled container.

After intensive investigations to achieve the above objects, the presentinventors have found that, by covering a container body with a shrinklabel using a heat-shrinkable opaque white film having a specific layerconfiguration, the resulting container can prevent its contents such asbeverages from light-induced deterioration, have, for example, a cleardesign, and show such an excellent appearance of the contents such asbeverages that the contents look their original colors withoutdiscomfort. The present invention has been achieved based on thesefindings.

Specifically, the present invention provides a heat-shrinkable opaquewhite film comprising a core layer; and white back and front layers, thecore layer having a chromatic color with low transparency to light atwavelengths of 380 to 500 nm or an achromatic color.

The core layer may contain at least one of black, yellow, red, and brownpigments. The heat-shrinkable opaque white film has, in a preferredembodiment, a transmission factor to light at wavelengths of 380 to 500nm of 5% or less. In another preferred embodiment of the heat-shrinkableopaque white film, the core layer has an achromatic color, and the filmhas a transmission factor to light at wavelengths of 200 to 600 nm of 3%or less. In yet another preferred embodiment of the heat-shrinkableopaque white film, the film has a W-value 60% or more on a surface ofthe front layer.

The heat-shrinkable opaque white film according to the present inventioncan be prepared, for example, by co-extruding back and front layers witha core layer and drawing the coextrudate.

The present invention also provides a shrink label comprising theheat-shrinkable opaque white film, and a preprinted ink label layerarranged on or above a surface of the front layer of the film.

The present invention further provides a labeled container comprising acontainer body; and the shrink label arranged on or above the containerbody.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross-sectional view showing an example of theshrink label according to the present invention.

FIG. 2 is a graph showing light transmission factors (transmittances) ofheat-shrinkable films obtained according to EXAMPLES 2, 3, and 4 andCOMPARATIVE EXAMPLE 1.

FIG. 3 is a graph showing light transmission factors (transmittances) ofheat-shrinkable films obtained according to COMPARATIVE EXAMPLE 3, andEXAMPLES 11 to 13.

FIG. 4 is a graph showing light transmission factors (transmittances) ofheat-shrinkable films obtained according to COMPARATIVE EXAMPLE 7, andEXAMPLES 18 to 22.

BEST MODE FOR CARRYING OUT THE INVENTION

The present invention will be illustrated in detail with reference tothe attached drawings according to necessity. The heat-shrinkable opaquewhite film according to the present invention comprises a core layer(central layer); and white back and front layers (front layer and backlayer). The core layer has a chromatic color having low transparency tolight (blocking light) at wavelengths of 380 to 500 nm or an achromaticcolor. The “front layer” means a layer which constitutes an outsidelayer when applied to a container and is to be printed typically with adesign upon the preparation of a label. The “back layer” means a layerlying near to a container when formed into a label. The heat-shrinkableopaque white film according to the present invention can prevent thecontents such as a beverage containing vitamins or beer fromdiscoloration and deterioration, since the core layer has an achromaticcolor or has imperviousness to light at wavelengths of 380 to 500 nm(the ultraviolet region to the blue-green visible light region). Adesign or such can be clearly printed when the film is formed into alabel, since the front layer is white and the film is thereby opaquewhite. In addition, when the label is applied to a container to form alabeled container, the contents in the container, such as beverages,look natural without deterioration of their original colors when viewedfrom the spout of the container, since the back layer is white. Theheat-shrinkable opaque white film may further comprise any other layeror layers within ranges not adversely affecting the properties such asheat-shrinkability, beauty and handleability, in addition to the corelayer and the back and front layers. Examples of the other layers aretransparent resin layers, other colored resin layers, and resin layersfor improving adhesion between layers, The shrink label according to thepresent invention comprises the heat-shrinkable opaque white film and apreprinted ink label layer arranged on or above a surface of the frontlayer. FIG. 1 is a schematic cross-sectional view showing an example ofthe shrink label according to the present invention. The illustratedshrink label comprises a heat-shrinkable opaque white film 4 and apreprinted ink label layer 5. The heat-shrinkable opaque white film 4comprises a white front layer 1, a core layer 2 having a chromatic colorwith low transparency to light at wavelengths of 380 to 500 nm or anachromatic color, and a white back layer 3. The preprinted ink labellayer 5 is arranged on a surface of the front layer 1 of the film 4.

Each of the front layer 1, the core layer 2, and the back layer 3 mayindependently comprise a heat-shrinkable film layer. Materials for suchheat-shrinkable film layers can be those generally used as materials forheat-shrinkable films, such as polyester resins, polystyrene resins,polyolefin resins, and poly(vinyl chloride) resins. Each of thesematerials can be used alone or in combination.

The polyester resins can be polyester resins prepared according to aconventional procedure such as condensation between a diol component anda dicarboxylic acid component (or a reactive derivative thereof, such asan ester). Examples of the diol component constituting the polyesterresins are aliphatic diols such as ethylene glycol, propylene glycol,1,3-propanediol, 2,2-dimethyl-1,3-propanediol,2-methyl-2-ethyl-1,3-propanediol, 2,2-diethyl-1,3-propanediol,2-ethyl-2-butyl-1,3-propanediol, 1,3-butanediol, 1,4-butanediol,1,6-hexanediol, and 2,2,4-trimethyl-1,6-hexanediol; thiodiethanol;polyalkylene glycols such as diethylene glycol, dipropylene glycol,polyethylene glycol, and polypropylene glycol; alicyclic diols such as1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, and1,4-cyclohexanedimethanol; and aromatic diols including ethylene oxideadducts of bisphenol compounds such as2,2-bis(4′-p-hydroxyethoxydiphenyl)propane andbis(4′-p-hydroxyethoxyphenyl)sulfone, as well as xylylene glycol. Eachof these diol components can be used alone or in combination.

Examples of the dicarboxylic acid component constituting the polyesterresins are aliphatic dicarboxylic acids such as oxalic acid, malonicacid, succinic acid, glutaric acid, adipic acid, pimelic acid, subericacid, azelaic acid, and sebacic acid; alicyclic dicarboxylic acids suchas 1,4-decahydronaphthalenedicarboxylic acid,1,5-decahydronaphthalenedicarboxylic acid,2,6-decahydronaphthalenedicarboxylic acid, 1,3-cyclohexanedicarboxylicacid, and 1,4-cyclohexanedicarboxylic acid; and aromatic dicarboxylicacids such as terephthalic acid, isophthalic acid,4,4′-biphenyldicarboxylic acid, trans-3,3′-stilbenedicarboxylic acid,trans-4,4′-stilbenedicarboxylic acid, 4,4′-dibenzyldicarboxylic acid,and naphthalenedicarboxylic acids such as 2,6-naphthalenedicarboxylicacid. Each of these dicarboxylic acid components can be used alone or incombination.

Preferred polyester resins are those prepared by using ethylene glycolas a main diol component, and an aromatic dicarboxylic acid such asterephthalic acid, isophthalic acid, or a naphthalenedicarboxylic acidas a main dicarboxylic acid component.

The polystyrene resins can be styrene-conjugated diene block copolymerssuch as styrene-butadiene-styrene block copolymers andstyrene-isoprene-styrene block copolymers; and mixtures of thestyrene-conjugated diene block copolymers with one or more otherpolymers such as polystyrenes or copolymers between styrene and anacrylic monomer such as (meth)acrylic ester. The styrene-conjugateddiene block copolymers may each have a styrene content of about 30 toabout 95 percent by weight and a conjugated diene content of about 5 toabout 70 percent by weight.

Each of the white front layer 1 and the white back layer 3 canindependently comprise the resin component and a white colorant. Suchwhite colorants are not limited and include white pigments such astitanium dioxide, antimony white, zinc sulfide, and zinc white. Amongthem, titanium dioxide has high whiteness to prevent the chromatic colorof the core layer 2 from being seen through and is particularlypreferred. The content of the white colorant in each of the front layer1 and the back layer 3 can be set as appropriate according typically tothe whiteness and cost and varies depending on the species of the whitecolorant. It is generally about 1 to about 20 percent by volume of thetotal volume of each layer. The content of titanium dioxide, forexample, per layer is generally about 5 to about 40 percent by weight,and preferably about 10 to about 25 percent by weight of the totalweight of each layer.

The average particle diameter of a white pigment such as titaniumdioxide, if used as the white colorant, is, for example, about 0.01 toabout 10 μm, preferably about 0.01 to about 5 μm, and more preferablyabout 0.1 to about 1 μm. If the average particle diameter is less than0.01 μm, dispersibility may be deteriorated. If it exceeds 10 μm, thefilm may have a rough surface and show a deteriorated appearance.

Adding a small amount of blue colorant such as a blue pigment to thewhite front layer 1 makes a yellow, red or brown color of the core layerbecome inconspicuous when viewed from the front side. The amount of theblue colorant is, for example, about 0.01 to about 0.5 percent by weightbased on the total weight of the front layer 1.

The white front layer 1 and the white back layer 3 include, in additionto a layer colored with the white colorant, a layer looking white,cloudy (milky) or opaque white as a result typically of foaming ormixing of two or more immiscible resins.

The core layer 2 includes an achromatic layer such as a black core layerand a grey core layer. The black core layer 2 can comprise the resincomponent and a black colorant. The black colorant is not specificallylimited and can be any of known black pigments, of which carbon black istypically preferred. The content of the black colorant in the black corelayer 2 can be set as appropriate in consideration typically of theimperviousness to light and cost within ranges not adversely affectingthe whiteness of the back and front layers of the film. It is generallypreferably 1×10⁻³ to 6 percent by volume based on the total volume ofthe core layer 2.

The amount of carbon black, if used as the black colorant, is generallyabout 0.01 to about 5 percent by weight, and preferably about 0.05 toabout 3 percent by weight based on the total weight of the core layer 2.The amount of carbon black is preferably 5×10⁻⁴ percent by weight ormore (e.g., about 5×10⁻⁴ to about 2.5 percent by weight) based on thetotal weight of the heat-shrinkable opaque white film. The content ofcarbon black per unit area of the opaque white film is preferably about1×10⁻⁴ g/m² to about 5 g/m², and more preferably about 1×10⁻³ g/m² toabout 1 g/m².

The average particle diameter of a black pigment such as carbon black,if used as the black colorant, is for example about 0.001 to about 10μm, and preferably about 0.01 to about 1 μm. If the average particlediameter is less than 0.001 μm, the dispersibility may often decrease.If it exceeds 10 μm, it may be difficult to achieve sufficientimperviousness to light.

The grey core layer 2 can comprise the resin component, a blackcolorant, and a white colorant. The black colorant and the whitecolorant herein can be any of those mentioned above. Among them, carbonblack and titanium dioxide are preferred as the black colorant and thewhite colorant, respectively. The content in the core layer 2 and theaverage particle diameter of the black colorant are as mentioned above.The content of the white colorant can be set as appropriate inconsideration typically of the whiteness and imperviousness to light ofthe film and cost and is generally about 1 to about 40 percent byweight, and preferably about 5 to about 25 percent by weight based onthe total weight of the core layer 2.

Such an achromatic core layer can be a layer of a metallic color such assilver, prepared by adding fine metal particles such as fine aluminumparticles and fine silver powder as a colorant.

Apart from the above configuration, the core layer 2 can comprise theresin component and a chromatic colorant which is capable of preventinglight (is impervious to light) at wavelengths of 380 to 500 nm frompassing through. The chromatic colorant can be, for example, any ofyellow pigments, red pigments, and brown pigments. Examples of theyellow pigments are inorganic pigments such as yellow ocher, aureolin,cadmium yellow, cadmium orange, chromium yellow, zinc yellow, Naplesyellow, and nickel yellow; and organic pigments such as azo pigments andgreenish yellow. Examples of the red pigments are inorganic pigmentssuch as cadmium red, cadmopone red, chromium red, vermilion, and ironoxide red; and organic pigments such as azo pigments, alizarin lake,quinacridone, and cochineal lake perylene. The brown pigments includeinorganic pigments such as umber, raw umber, burnt umber, yellow ocher,Vandyke brown, sienna, raw sienna, burnt sienna, and iron oxide red; andorganic pigments such as sepia. Each of these chromatic colorants can beused alone or in combination. The core layer having a chromatic colorwith low transparency to light at wavelengths of 380 to 500 nm can be alayer of a metallic color incorporated with fine metal particles as acolorant.

The content of the chromatic colorant in the core layer 2 can be set asappropriate in consideration typically of the imperviousness to light(light blocking property) and cost within ranges not adversely affectingthe whiteness of the back and front layers of the film. It is generallyabout 0.01 to about 20 percent by weight, and preferably about 0.05 toabout 15 percent by weight based on the total weight of the core layer2. The amount of the chromatic colorant is preferably 5×10⁻⁴ percent byweight or more (e.g., about 5×10⁻⁴ to about 5 percent by weight) basedon the total weight of the heat-shrinkable opaque white film. Thecontent of the chromatic colorant per unit area of the opaque white filmis preferably about 1×10⁻⁴ g/m² to about 5 g/m², and more preferablyabout 1×10⁻³ g/m² to about 1 g/m².

While varying depending on its species, the average particle diameter ofthe chromatic colorant generally about 0.01 to about 1 μm. If theaverage particle diameter exceeds 1 μm, sufficient imperviousness tolight may not be satisfactorily obtained. If it is less than 0.01 μm,the dispersibility may often decrease. When the colorant is a yellowpigment, the average particle diameter is particularly preferably withinthe range of 0.3 to 0.6 μm. In the case of a brown pigment, the averageparticle diameter is particularly preferably in the range of 0.4 to 0.7μm.

The core layer 2 may further comprise a white colorant such as a whitepigment, for increasing the whiteness. When a red pigment and/or a brownpigment is used as the chromatic colorant, the chromatic color of thecore layer 2 may slightly appear on the surface of the film. Thechromatic color of the core layer 2 can be substantially fully masked byadding a white colorant to the core layer 2. The white colorant hereincan be as mentioned above, of which titanium dioxide is preferred. Thecontent of the white colorant, if added, is, for example, about 0.1 toabout 40 percent by weight, and preferably about 5 to about 25 percentby weight based on the total weight of the core layer 2.

It is not always necessary to use a transparent material as a resinmaterial for constituting the core layer 2. Consequently, recycledmaterials such as failed printed films, borders on the periphery offilms, and film pieces with printed portions can be effectively used asthe resin material. This is a very economical advantage. In this case,the amount of the recycled material can be set as appropriate withinranges not adversely affecting properties such as imperviousness tolight and heat-shrinkability and is generally preferably 30 percent byweight or less (e.g., about 1 to about 30 percent by weight) of thetotal amount of resin materials constituting respective layers.

In the heat-shrinkable opaque white film 4 according to the presentinvention, it is not always necessary to constitute all the front layer1, the core layer 2 and the back layer 3 as heat-shrinkable film layers,as long as the heat-shrinkable opaque white film as a whole isheat-shrinkable. Heat-shrinkability can be imparted to the opaque whitefilm 4, for example, by constituting one or two of the three layers asheat-shrinkable film layers, or arranging a heat-shrinkable film layerin addition to the three layers. Each of the front layer 1, the corelayer 2, and the back layer 3 can comprise a printed layer or a coatinglayer, if not a heat-shrinkable film layer. The front layer 1 and theback layer 3 can be formed, for example, by printing both sides (backand front sides) of an achromatic or chromatic heat-shrinkable filmlayer to be the core layer 2 with an ink containing a white pigment suchas titanium dioxide according to a conventional printing procedure suchas gravure printing. Likewise, the core layer 2 can be formed byprinting a white heat-shrinkable film layer to be the front layer 1 withan ink containing an achromatic or chromatic colorant according to aconventional printing procedure such as gravure printing. When the filmcomprise two or more heat-shrinkable film layers, resins constitutingthese layers may be of different species but are preferably of the samespecies from the viewpoints typically of workability and recyclingproperty.

Representative layer configurations of the heat-shrinkable opaque whitefilm 4 include (1) white heat-shrinkable film layer (front layer)/black,grey or chromatic heat-shrinkable film layer (core layer)/whiteheat-shrinkable film layer (back layer); (2) white heat-shrinkable filmlayer (front layer)/black, grey or chromatic heat-shrinkable film layer(core layer)/white preprinted layer (back layer); and (3) whitepreprinted layer (front layer)/black, grey or chromatic heat-shrinkablefilm layer (core layer)/white heat-shrinkable film layer (back layer).Preferred layer configurations in the present invention are those inwhich at least the core layer 2 is a black, grey or chromaticheat-shrinkable film layer. In these layer configurations, cost can bereduced. This is because, for example, a sufficient density can beachieved by directly kneading an achromatic or chromatic colorant into aresin. The achromatic or chromatic core layer can be formed by using arecycled material. When it is a black core layer, a larger amount of arecycled material can be used. It is preferred to constitute all thefront layer 1, the core layer 2, and the back layer 3 as heat-shrinkablefilm layers. This is because, for example, (i) the three layers can beformed by an easy and convenient procedure of coextrusion,heat-shrinkability can be imparted by subjecting the extruded threelayers to drawing simultaneously, and the heat-shrinkable opaque whitefilm can thereby be produced with high production efficiently; (ii) if aprinting process such as gravure printing is employed, a heat-shrinkablefilm layer is dissolved or deteriorated with a solvent in ink, the filmlayer is difficult to have a sufficiently high whiteness and requireshigher cost; and (iii) when a preprinted layer is highly shrunk, it mayhave ink cracking and have a deteriorated appearance.

Each of the front layer 1, the core layer 2, and the back layer 3constituting the heat-shrinkable opaque white film 4 may furthercomprise any of additives according to necessity. Such additives includelubricants, fillers, thermostabilizers, antioxidants, ultravioletabsorbents, antistatics, and flame-retarders.

The thickness of the heat-shrinkable opaque white film 4 can be set asappropriate within ranges not adversely affecting properties such ashandleability, appearance, imperviousness to light, andheat-shrinkability. It is, for example, about 10 to about 200 μm, andpreferably about 30 to about 70 μm. The thickness of the core layer 2 isgenerally about 1% to about 80%, preferably about 5% to about 50%, andspecifically preferably about 5% to about 30% of the total thickness ofthe heat-shrinkable opaque white film 4.

The heat-shrinkable opaque white film 4 can be prepared according to aconventional procedure for preparing multilayer films, such ascoextrusion and lamination. More specifically, a heat-shrinkable opaquewhite film having the layer configuration (1), i.e., whiteheat-shrinkable film layer (front layer)/black, grey or chromaticheat-shrinkable film layer (core layer)/white heat-shrinkable film layer(back layer), can be prepared by subjecting a resin composition (A)containing a resin and a white colorant, a resin composition (B)containing a resin and at least a black colorant or a chromaticcolorant, and a resin composition (C) containing a resin and a whitecolorant to melt-coextrusion using an extruder equipped with a T-die orannular die, cooling the extrudate typically using a chill roll, anddrawing the cooled extrudate. Drawing can be carried out according toany of tenter drawing and tube drawing. Drawing can be any of biaxialdrawing and uniaxial drawing (uniaxial stretching). The percent ofstretch can be set as appropriate according to a desired heat-shrinkagepercentage. This method comprising the steps of molding a film bycoextrusion and drawing the molded film is preferred, because amultilayer film can be easily obtained and the individual layers can bedrawn under the same conditions. Melt coextrusion to yield a five-layerconfiguration in which each of the front layer and the back layer has atwo-layer configuration is also acceptable.

Another heat-shrinkable opaque white film having the layer configuration(1) can be prepared by preparing individual heat-shrinkable films forindividual layers by extruding in different steps, and laminating theindividual films by dry lamination. According to this method, filmscomprising resins that are resistant to coextrusion can be laminated,although the resulting multilayer film has adhesive layers between theindividual layers and thereby has lower shrinkability than that in thefilm of coextruded layers.

A heat-shrinkable opaque white film having the layer configuration (2),i.e., white heat-shrinkable film layer (front layer)/black, grey orchromatic heat-shrinkable film layer (core layer)/white preprinted layer(back layer), can be produced, for example, by subjecting a resincomposition (A) containing a resin and a white colorant, and a resincomposition (B) containing a resin and at least a black colorant or achromatic colorant to melt coextrusion using an extruder equipped with aT-die or annular die, cooling the extrudate typically with a chill roll,subjecting the cooled extrudate to drawing in the same manner as above,and forming one or more layers of white printing to a back side of thelayer formed from the resin composition (B) (corresponding to the corelayer) typically by gravure printing with a white ink. When a whitepreprinted layer is formed as the back layer typically by gravureprinting, the sliding property of the surface of the back layer can beincreased by adding, for example, a lubricant to the white ink.

The heat-shrinkage percentage of the heat-shrinkable opaque white film 4can be set as appropriate according typically to the shape of containerto be applied and is generally 15% or more at least in one direction.For example, the heat-shrinkage percentage of a uniaxially stretchedfilm is generally about 20% to about 90%, and preferably about 30% toabout 70% in a main drawing direction when the film is immersed in hotwater at 90° C. for ten seconds. The heat-shrinkage percentage of abiaxially stretched film is generally about 20% to about 90%, andpreferably about 30% to about 70% in one direction (e.g., widthwisedirection) and is generally about 1% to about 30%, and preferably about3% to about 15% in the other direction (e.g., lengthwise direction) whenthe film is immersed in hot water at 90° C. for ten seconds.

When the heat-shrinkable opaque white film 4 according to the presentinvention has an achromatic layer as the core layer 2, it can have avery low light transmission factor in the ultraviolet and visible-lightregions. The light transmission factor, for example, at wavelengths of200 to 400 nm is generally 3% or less, and preferably 1% or less. Thelight transmission factor at wavelengths of 400 to 600 nm is generally5% or less, and 3% or less. The light transmission factor can beadjusted, for example, by adjusting the content of a black colorant orwhite colorant in the core layer 2 and/or the thickness of the corelayer 2.

When the heat-shrinkable opaque white film 4 according to the presentinvention has a layer of a chromatic color with low transparency tolight at wavelengths of 380 to 500 nm as the core layer 2, the film canhave a very low light transmission factor in the ultraviolet andblue-green visible-light regions. The light transmission factor atwavelengths of 380 to 500 nm is, for example, 5% or less, and preferably3% or less. This light transmission factor can be adjusted bycontrolling the content of a yellow, red or brown colorant in the corelayer 2 and/or the thickness of the core layer 2.

The preprinted ink label layer 5 is a layer having, for example,character information such as trade name or design as a result ofprinting. It can be formed on a surface of the front layer 1 of theheat-shrinkable opaque white film 4 using an ink according to aconventional printing procedure such as gravure printing, flexographicprinting, or screen printing. The ink is not specifically limited, canbe a suitable ink selected from, for example, solvent-based inks andwater-based inks. Each of these inks can be used alone or incombination. The thickness of the preprinted ink label layer can beselected within ranges of, for example, about 0.5 to about 20 μm, andpreferably about 1 to about 10 μm. The preprinted ink label layer cancomprise a single layer or plural layers. An overcoat layer can bearranged on the surface of the preprinted ink label layer typically forprotecting the preprinted ink label layer. The surface (inside surfacewith respect to the container) of the back layer 3 may be subjected toprinting and indication typically of characters or may have a slidingcoat layer using a transparent ink.

The shrink label according to the present invention can be formed into atubular or cylindrical shrink label, for example, by forming thepreprinted ink label layer 5 on a surface of the front layer 1 of theheat-shrinkable opaque white film 4, cutting the resulting article to along slit with a desired width, rolling the cut article into a cylinderso that the preprinted ink label layer 5 faces outward and the maindrawing direction is a peripheral direction, sticking the both endstypically with an adhesive or a solvent, or by heat sealing, and cuttingthe article to a desired length.

The labeled container according to the present invention comprises acontainer body and the shrink label according to the present inventionapplied on or above the container body. The container body is notspecifically limited, as long as it is formed from a light-transmittablematerial. It can be any article such as plastic bottles and glassbottles. Examples of materials for the plastic bottles are thermoplasticresins that can undergo blow molding, including polyester resins such aspoly(ethylene terephthalate)s and poly(ethylene naphthalate)s;polystyrene resins such as polystyrenes; polyolefin resins such aspolyethylenes and polypropylenes; poly(vinyl chloride)s; polycarbonates;and arylate resins. Each of these materials can be used alone or incombination.

The labeled container according to the present invention can beproduced, for example, by supplying the tubular shrink label to anautomatic labeling apparatus, cutting the label to a desired lengthaccording to necessity, allowing the label to fit over an article to beapplied (container body) continuously, and subjecting the same to heatshrinkage by allowing the same to pass through a steam tunnel or hot-airtunnel at a predetermined temperature. The contents such as beveragescan be charged into the container before or after the shrink wrapping.

The labeled container according to the present invention is suitable,for example, as containers for beverages that are susceptible todiscoloration and deterioration caused by light, including alcoholicbeverages such as beer, sake, and wine, milk, milky drinks, green tea,and beverages containing vitamins. The labeled container is specificallypreferably used as containers for white or pale color (e.g., paleyellow) contents, such as milk or milky drinks, as the back layer of thelabel is white.

The heat-shrinkable opaque white film according to the present inventionhas a core layer of black, grey, or a chromatic color with lowtransparency to light at wavelengths of 380 to 500 nm (the ultravioletto blue-green visible-light regions), can thereby prevent the contentssuch as beverages from discoloration and deterioration. It has a whitefront layer, on which an indication print such as of a design can beformed clearly. In addition, when a shrink label using theheat-shrinkable opaque white film is applied to a container, the filmhas a white back layer, thereby enables clear and sharp looking of thecontents and yields excellent appearance of the contents.

EXAMPLES

The present invention will be illustrated in further detail withreference to several examples below which by no means limit the scope ofthe present invention.

Example 1

A polystyrene resin composition [(titanium dioxide)/(polystyrene resin)(weight ratio)=5/95] for forming back and front layers was prepared byblending a styrene-conjugated diene block copolymer [a product of DenkiKagaku Kogyo Kabushiki Kaisha under the trade name of “CLEAREN 530L”]with a polystyrene (GPPS) [a product of SUMIKA COLOR CO., LTD. under thetrade name of “SPSM-7G971”] master batch containing 60 percent by weightof titanium dioxide (TiO₂). A polystyrene resin composition [(carbonblack)/(polystyrene resin) (weight ratio)=1/99] for forming a core layerwas prepared by blending a styrene-conjugated diene block copolymer [aproduct of Denki Kagaku Kogyo Kabushiki Kaisha under the trade name of“CLEAREN 530L”] with a polystyrene (GPPS) [a product of SUMIKA COLORCO., LTD. under the trade name of “SPAB-851”] master batch containing 40percent by weight of carbon black. These resin compositions were fed toan extruder equipped with a T-die and were coextruded at a temperatureof 220° C., the extrudate was cooled with a chill roll and was drawn 1.2times in a lengthwise direction and 4 times in a widthwise direction toyield a long heat-shrinkable film. This film has a three-layerconfiguration and has a thickness of 50 μm (ratio of thickness oflayers: (front layer)/(core layer)/(back layer)=4/3/4).

Design print and transparent overcoat were applied to one side (asurface of the front layer) of the long heat-shrinkable film using agravure printing machine to thereby yield a shrink label. The shrinklabel was slit in a lengthwise direction to a predetermined length toyield plural rolls. Each roll was rewound, was rolled so that thedesigned surface is outside and the widthwise direction of the film is aperipheral direction, the both ends of which were adhered with eachother and thereby yielded a long tube. This was cut to an appropriatelength and thereby yielded a tubular shrink label. The tubular shrinklabel was allowed to fit for the body of a PET bottle containing milkand having an inner capacity of 280 ml and was shrunk by passing througha steam tunnel. Thus, a labeled container was produced.

Example 2

A heat-shrinkable film having a three-layer configuration was preparedby the procedure of EXAMPLE 1, except that the heat-shrinkable film hada three-layer configuration having a ratio of thickness of layers:(front layer)/(core layer)/(back layer) of 3/1/3. Using thisheat-shrinkable film, a shrink label and a labeled container wereproduced by the procedure of EXAMPLE 1.

Example 3

A heat-shrinkable film having a three-layer configuration was preparedby the procedure of EXAMPLE 2, except for using a polystyrene resincomposition for forming back and front layers having a compositionalratio (by weight) of (titanium dioxide)/(polystyrene resin) (weightratio) of 10/90. Using this heat-shrinkable film, a shrink label and alabeled container were produced by the procedure of EXAMPLE 1.

Example 4

A heat-shrinkable film having a three-layer configuration was preparedby the procedure of EXAMPLE 2, except for using a polystyrene resincomposition for forming back and front layers having a compositionalratio (by weight) of (titanium dioxide)/(polystyrene resin) (weightratio) of 20/80. Using this heat-shrinkable film, a shrink label and alabeled container were produced by the procedure of EXAMPLE 1.

Example 5

A heat-shrinkable film having a three-layer configuration was preparedby the procedure of EXAMPLE 4, except for using a polystyrene resincomposition for forming a core layer having a compositional ratio (byweight) of (carbon black)/(polystyrene resin) (weight ratio) of0.1/99.9. Using this heat-shrinkable film, a shrink label and a labeledcontainer were produced by the procedure of EXAMPLE 1.

Example 6

A heat-shrinkable film having a three-layer configuration was preparedby the procedure of EXAMPLE 4, except for using a polystyrene resincomposition for forming a core layer having a compositional ratio (byweight) of (carbon black)/(polystyrene resin) (weight ratio) of0.2/99.8. Using this heat-shrinkable film, a shrink label and a labeledcontainer were produced by the procedure of EXAMPLE 1.

Comparative Example 1

A heat-shrinkable film having a three-layer configuration was preparedby the procedure of EXAMPLE 2, except for using a polystyrene resincomposition for forming a core layer having a compositional ratio (byweight) of (carbon black)/(polystyrene resin) (weight ratio) of 0/100.Using this heat-shrinkable film, a shrink label and a labeled containerwere produced by the procedure of EXAMPLE 1.

Comparative Example 2

A heat-shrinkable film having a three-layer configuration was preparedby the procedure of EXAMPLE 2, except for using a polystyrene resincomposition for forming a core layer having a compositional ratio (byweight) of (carbon black)/(polystyrene resin) (weight ratio) of 5/95.Using this heat-shrinkable film, a shrink label and a labeled containerwere produced by the procedure of EXAMPLE 1.

Example 7

A polystyrene resin composition [(titanium dioxide)/(polystyrene resin)(weight ratio)=20/80] for forming back and front layers was prepared byblending a styrene-conjugated diene block copolymer [a product of DenkiKagaku Kogyo Kabushiki Kaisha under the trade name of “CLEAREN 530L”]with a polystyrene (GPPS) [a product of SUMIKA COLOR CO., LTD. under thetrade name of “SPSM-7G971”]white master batch containing 60 percent byweight of titanium dioxide (TiO₂). Separately, a polystyrene resincomposition [(titanium dioxide)/(carbon black)/(polystyrene resin)(weight ratio)=20/0.05/79.95] for forming a core layer was prepared byblending a styrene-conjugated diene block copolymer [a product of DenkiKagaku Kogyo Kabushiki Kaisha under the trade name of “CLEAREN 530L”]with the white master batch and a polystyrene (GPPS) [a product ofSUMIKA COLOR CO., LTD. under the trade name of “SPAB-851”] master batchcontaining 40 percent by weight of carbon black. These resincompositions were fed to an extruder equipped with a T-die and werecoextruded at a temperature of 210° C., the extrudate was cooled with achill roll and was drawn 1.2 times in a lengthwise direction and 4 timesin a widthwise direction to yield a long heat-shrinkable film. This filmhas a three-layer configuration and has a thickness of 50 μm (ratio ofthickness of layers: (front layer)/(core layer)/(back layer)=3/1/3).

Using this heat-shrinkable film, a shrink label and a labeled containerwere produced by the procedure of EXAMPLE 1.

Example 8

A heat-shrinkable film having a three-layer configuration was preparedby the procedure of EXAMPLE 7, except for using a polystyrene resincomposition for forming a core layer having a compositional ratio (byweight) of (titanium dioxide)/(carbon black)/(polystyrene resin) of20/0.2/79.8. Using this heat-shrinkable film, a shrink label and alabeled container were produced by the procedure of EXAMPLE 1.

Example 9

A heat-shrinkable film having a three-layer configuration was preparedby the procedure of EXAMPLE 7, except for using a polystyrene resincomposition for forming a core layer having a compositional ratio (byweight) of (titanium dioxide)/(carbon black)/(polystyrene resin) of20/1/79. Using this heat-shrinkable film, a shrink label and a labeledcontainer were produced by the procedure of EXAMPLE 1.

Example 10

A heat-shrinkable film having a three-layer configuration was preparedby the procedure of EXAMPLE 7, except for using a polystyrene resincomposition for forming a core layer having a compositional ratio (byweight) of (titanium dioxide)/(carbon black)/(polystyrene resin) of20/5/75. Using this heat-shrinkable film, a shrink label and a labeledcontainer were produced by the procedure of EXAMPLE 1.

Example 11

A polystyrene resin composition [(titanium dioxide)/(polystyrene resin)(weight ratio)=24/76] for forming back and front layers was prepared byblending a styrene-conjugated diene block copolymer [a product of DenkiKagaku Kogyo Kabushiki Kaisha under the trade name of “CLEAREN 530L”]with a polystyrene (GPPS) [a product of SUMIKA COLOR CO., LTD. under thetrade name of “SPSM-7G971”] white master batch containing 60 percent byweight of titanium dioxide (TiO₂). Separately, a polystyrene resincomposition for forming a core layer [(titanium dioxide)/(carbonblack)/(polystyrene resin) (weight ratio)=20/0.2/79.8] was prepared byblending a styrene-conjugated diene block copolymer [a product of DenkiKagaku Kogyo Kabushiki Kaisha under the trade name of “CLEAREN 530L”]with the white master batch and a polystyrene (GPPS) [a product ofSUMIKA COLOR CO., LTD. under the trade name of “SPAB-851”] master batchcontaining 40 percent by weight of carbon black. These resincompositions were fed to an extruder equipped with a T-die and werecoextruded at a temperature of 210° C., the extrudate was cooled with achill roll and was drawn 1.2 times in a lengthwise direction and 4 timesin a widthwise direction to yield a long heat-shrinkable film. This filmhas a three-layer configuration and has a thickness of 50 μm (ratio ofthickness of layers: (front layer)/(core layer)/(back layer)=3/1/3).

Using this heat-shrinkable film, a shrink label and a labeled containerwere produced by the procedure of EXAMPLE 1.

Example 12

A heat-shrinkable film having a three-layer configuration was preparedby the procedure of EXAMPLE 11, except for using a polystyrene resincomposition for forming a core layer having a compositional ratio (byweight) of (titanium dioxide)/(carbon black)/(polystyrene resin) of20/0.15/79.85. Using this heat-shrinkable film, a shrink label and alabeled container were produced by the procedure of EXAMPLE 1.

Example 13

A heat-shrinkable film having a three-layer configuration was preparedby the procedure of EXAMPLE 11, except for using a polystyrene resincomposition for forming a core layer having a compositional ratio (byweight) of (titanium dioxide)/(carbon black)/(polystyrene resin) of20/0.1/79.9. Using this heat-shrinkable film, a shrink label and alabeled container were produced by the procedure of EXAMPLE 1.

Comparative Example 3

A heat-shrinkable film having a three-layer configuration was preparedby the procedure of EXAMPLE 11, except for using a polystyrene resincomposition for forming a core layer having a compositional ratio (byweight) of (titanium dioxide)/(carbon black)/(polystyrene resin) of0/0/100. Using this heat-shrinkable film, a shrink label and a labeledcontainer were produced by the procedure of EXAMPLE 1.

Comparative Example 4

A heat-shrinkable film having a three-layer configuration was preparedby the procedure of EXAMPLE 11, except for using a polystyrene resincomposition for forming a core layer having a compositional ratio (byweight) of (titanium dioxide)/(carbon black)/(polystyrene resin) of20/10/70. Using this heat-shrinkable film, a shrink label and a labeledcontainer were produced by the procedure of EXAMPLE 1.

Example 14

A poly(ethylene terephthalate) resin composition for forming back andfront layers [(titanium dioxide)/(PET resin) (weight ratio)=20/80] wasprepared by blending a poly(ethylene terephthalate) resin (PET resin) [aproduct of Eastman Chemical Company under the trade name of “Embrace”]with a PET resin [a product of SUMIKA COLOR CO., LTD. under the tradename of “EPM-7670”] white master batch containing 50 percent by weightof titanium dioxide (TiO₂). Separately, a poly(ethylene terephthalate)resin composition for forming a core layer [(titanium dioxide)/carbonblack)/(PET resin) (weight ratio)=20/0.05/79.95] was prepared byblending a PET resin [a product of Eastman Chemical Company under thetrade name of “Embrace”] with the white master batch, and a PET resin [aproduct of SUMIKA COLOR CO., LTD. under the trade name of “EPM-8400”]master batch containing 30 percent by weight of carbon black. Theseresin compositions were fed to an extruder equipped with a T-die, werecoextruded at a temperature of 250° C., the extrudate was cooled with achill roll, was drawn 4.5 times in a widthwise direction and therebyyielded a long heat-shrinkable film having a three-layer configurationand having a thickness of 50 μm (ratio of thickness of layers: (frontlayer)/(core layer)/(back layer)=3/1/3).

Using this heat-shrinkable film, a shrink label and a labeled containerwere produced by the procedure of EXAMPLE 1.

Example 15

A heat-shrinkable film having a three-layer configuration was preparedby the procedure of EXAMPLE 14, except for using a poly(ethyleneterephthalate) resin composition for forming a core layer having acompositional ratio (by weight) of (titanium dioxide)/carbon black)/(PETresin) of 20/0.2/79.8. Using this heat-shrinkable film, a shrink labeland a labeled container were produced by the procedure of EXAMPLE 1.

Example 16

A heat-shrinkable film having a three-layer configuration was preparedby the procedure of EXAMPLE 14, except for using a poly(ethyleneterephthalate) resin composition for forming a core layer having acompositional ratio (by weight) of (titanium dioxide)/carbon black)/(PETresin) of 20/1/79. Using this heat-shrinkable film, a shrink label and alabeled container were produced by the procedure of EXAMPLE 1.

Example 17

A heat-shrinkable film having a three-layer configuration was preparedby the procedure of EXAMPLE 14, except for using a poly(ethyleneterephthalate) resin composition for forming a core layer having acompositional ratio (by weight) of (titanium dioxide)/carbon black)/(PETresin) of 20/5/75. Using this heat-shrinkable film, a shrink label and alabeled container were produced by the procedure of EXAMPLE 1.

Comparative Example 5

A heat-shrinkable film having a three-layer configuration was preparedby the procedure of EXAMPLE 14, except for using a poly(ethyleneterephthalate) resin composition for forming a core layer having acompositional ratio (by weight) of (titanium dioxide)/carbon black)/(PETresin) of 0/0/100. Using this heat-shrinkable film, a shrink label and alabeled container were produced by the procedure of EXAMPLE 1.

Comparative Example 6

A heat-shrinkable film having a two-layer configuration was prepared bythe procedure of EXAMPLE 14, except for using a poly(ethyleneterephthalate) resin composition for forming a core layer having acompositional ratio (by weight) of (titanium dioxide)/carbon black)/(PETresin) of 0/5/95 and for not forming a back layer. Using thisheat-shrinkable film, a shrink label and a labeled container wereproduced by the procedure of EXAMPLE 1.

Example 18

A polystyrene resin composition for forming back and front layers[(titanium dioxide)/(polystyrene resin) (weight ratio)=10/90] wasprepared by blending a styrene-conjugated diene block copolymer [aproduct of Denki Kagaku Kogyo Kabushiki Kaisha under the trade name of“CLEAREN 530L”] with a polystyrene (GPPS) [a product of SUMIKA COLORCO., LTD. under the trade name of “SPSM-7G971”] master batch containing60 percent by weight of titanium dioxide (TiO₂). Separately, apolystyrene resin composition for forming a core layer [(redpigment)/(polystyrene resin) (weight ratio)=0.5/99.5] was prepared byadding to a styrene-conjugated diene block copolymer [a product of DenkiKagaku Kogyo Kabushiki Kaisha under the trade name of “CLEAREN 530L”]0.5 percent by weight of liquid paraffin as a spreader, and then addinga red pigment [a product of SUMIKA COLOR CO., LTD. under the trade nameof “SHPA-102”, an organic pigment (azo pigment)] thereto. These resincompositions were fed to an extruder equipped with a T-die and werecoextruded at a temperature of 220° C., the extrudate was cooled with achill roll and was drawn 1.2 times in a lengthwise direction and 4 timesin a widthwise direction to yield a long heat-shrinkable film. This filmhas a three-layer configuration and has a thickness of 50 μm (ratio ofthickness of layers: (front layer)/(core layer)/(back layer)=2/1/2).

Using this heat-shrinkable film, a shrink label and a labeled containerwere produced by the procedure of EXAMPLE 1

Example 19

A heat-shrinkable film having a three-layer configuration was preparedby the procedure of EXAMPLE 18, except for using a yellow pigment [aproduct of SUMIKA COLOR CO., LTD. under the trade name of “SHPA-347”, aninorganic pigment (chromium yellow)] instead of the red pigment [aproduct of SUMIKA COLOR CO., LTD. under the trade name of “SHPA-102”, anorganic pigment] to thereby prepare a polystyrene resin composition forforming a core layer [(yellow pigment)/(polystyrene resin) (weightratio)=1.0/99.0]. Using this heat-shrinkable film, a shrink label and alabeled container were produced by the procedure of EXAMPLE 1.

Example 20

A heat-shrinkable film having a three-layer configuration was preparedby the procedure of EXAMPLE 18, except for using a brown pigment [aproduct of SUMIKA COLOR CO., LTD. under the trade name of “SHPA-918”, aninorganic pigment (iron oxide red)] instead of the red pigment [aproduct of SUMIKA COLOR CO., LTD. under the trade name of “SHPA-102”, anorganic pigment] to thereby prepare a polystyrene resin composition forforming a core layer [(brown pigment)/(polystyrene resin) (weightratio)=1.0/99.0]. Using this heat-shrinkable film, a shrink label and alabeled container were produced by the procedure of EXAMPLE 1.

Example 21

A heat-shrinkable film having a three-layer configuration was preparedby the procedure of EXAMPLE 18, except for using a white pigment[titanium dioxide (TiO₂)] in addition to the red pigment [a product ofSUMIKA COLOR CO., LTD. under the trade name of “SHPA-102”, an organicpigment] to thereby prepare a polystyrene resin composition for forminga core layer [(red pigment)/(white pigment)/(polystyrene resin) (weightratio)=0.5/5.0/94.5]. Using this heat-shrinkable film, a shrink labeland a labeled container were produced by the procedure of EXAMPLE 1.

Example 22

A heat-shrinkable film having a three-layer configuration was preparedby the procedure of EXAMPLE 18, except for using a brown pigment [aproduct of SUMIKA COLOR CO., LTD. under the trade name of “SHPA-918”, aninorganic pigment (iron oxide red)] and a white pigment [titaniumdioxide (TiO₂)] instead of the red pigment [a product of SUMIKA COLORCO., LTD. under the trade name of “SHPA-102”, an organic pigment] tothereby yield a polystyrene resin composition for forming a core layer[(brown pigment)/(white pigment)/(polystyrene resin) (weightratio)=1.0/5.0/94.0]. Using this heat-shrinkable film, a shrink labeland a labeled container were produced by the procedure of EXAMPLE 1.

Comparative Example 7

A heat-shrinkable film having a three-layer configuration was preparedby the procedure of EXAMPLE 18, except for preparing a polystyrene resincomposition for forming a core layer [(red pigment)/(polystyrene resin)(weight ratio)=0/100] without using the red pigment [a product of SUMIKACOLOR CO., LTD. under the trade name of “SHPA-102”, an organic pigment].Using this heat-shrinkable film, a shrink label and a labeled containerwere produced by the procedure of EXAMPLE 1.

Evaluation Test

The heat-shrinkable films prepared according to the examples andcomparative examples were subjected to the following evaluation test.The results are shown in Table 1. In Table 1, “PS”, “CB”, “TiO₂”, and“PET” represent a polystyrene resin, carbon black, titanium dioxide, anda poly(ethylene terephthalate) resin, respectively. The “front”, “core”,and “back” in the film composition represent resin compositionsconstituting the front layer, core layer, and back layer, respectively.The numerical values in Table 1 are percentages.

(Imperviousness to Light)

The light transmission factor at wavelengths of 200 to 1000 nm of eachof the heat-shrinkable films prepared according to the examples andcomparative examples was determined using anear-infrared-ultraviolet-visible spectrophotometer [a product ofShimadzu Corporation under the trade name of “UV-3101PC”], and theimperviousness to light at specific wavelength was evaluated accordingto the following criteria.

FIG. 2 shows the measurements of the light transmission factor of theheat-shrinkable films prepared according to EXAMPLES 2, 3, and 4, andCOMPARATIVE EXAMPLE 1, respectively. The symbols a, b, c, and d in FIG.2 represent the measurements of the heat-shrinkable films according toEXAMPLE 4, EXAMPLE 3, EXAMPLE 2, and COMPARATIVE EXAMPLE 1,respectively.

FIG. 3 shows measurements a, b, c, and d of the light transmissionfactor (transmittance) of the heat-shrinkable films prepared accordingto EXAMPLES 11, 12, and 13, and COMPARATIVE EXAMPLE 3, respectively.

FIG. 4 shows measurements a, b, c, d, e, and f of the light transmissionfactor (transmittance) of the heat-shrinkable films prepared accordingto COMPARATIVE EXAMPLE 7, and EXAMPLES 18, 19, 20, 21 and 22,respectively. [Criteria for EXAMPLES 1 to 17 and COMPARATIVE EXAMPLES 1to 6 (Tables 1 to 3)] AA: The light transmission factor at wavelengthsof 200 to 600 nm is 3% or less.

A: The light transmission factor at wavelengths of 200 to 600 nm is morethan 3% and 5% or less.

C: The light transmission factor at wavelengths of 200 to 600 nm is morethan 5%.

[Criteria for EXAMPLES 18 to 22 and COMPARATIVE EXAMPLE 7 (Table 4)]

A: The light transmission factor at wavelengths of 380 to 500 nm is 5%or less.

C: The light transmission factor at wavelengths of 380 to 500 nm is morethan 5%.

(Whiteness)

A W-value of each of the heat-shrinkable films prepared according to theexamples and comparative examples was determined on a surface of thefront layer using an ultraviolet-visible spectrophotometer [a product ofShimadzu Corporation under the trade name of “UV-2450”] according toJapanese Industrial Standards (JIS) Z 8715. The whiteness of the filmswas evaluated according to the following criteria, while defining themeasured W-value of the standard white board (a product of Japan ColorResearch Institute) being 100.

AA: W-value of 80 or more

A: W-value of 75 or more and less than 80

B: W-value of 60 or more and less than 75

C: W-value of less than 60

These were visually evaluated and were found that those having a W-valueof 75 or more (AA and A) each have a white surface with a sharp design,in which black, grey or a chromatic color of the core layer issubstantially trivial; those having a W-value of 60 or more and lessthan 75 (B) each have a surface of slightly grayish white or a slightlychromatic color but with a sharp design; and those having a W-value lessthan 60 (C) show a blackish grey surface with a darkened design or asurface with a clear chromatic color.

(Appearance of contents)

The contents (milk) was viewed through a spout of the labeled containersproduced according to the examples and comparative examples, and theappearance of the contents was visually evaluated according to thefollowing criteria.

A: The milk looks white and fresh.

C: The milk looks blackish or chromatic. TABLE 1 Comparative ExampleExample 1 2 3 4 5 6 1 2 Front layer (%) PS 95 95 90 80 80 80 95 95 TiO₂5 5 10 20 20 20 5 5 Core layer (%) PS 99 99 99 99 99.9 99.8 100 95 CB 11 1 1 0.1 0.2 0 5 Film configuration front/core/ front/core/backfront/core/back (ratio of layers) back (3/1/3) (3/1/3) (4/3/4)Imperviousness to light AA AA AA AA A AA C AA (numeral in FIG. 2) (c)(b) (a) (d) Whiteness B B A A AA AA AA C Heat shrinkage (%) 53 53 52 5254 54 55 51 Appearance of contents A A A A A A A C

TABLE 2 Comparative Example Example 7 8 9 10 11 12 13 3 4 Front layer(%) PS 80 80 80 80 76 76 76 76 76 TiO₂ 20 20 20 20 24 24 24 24 24 Corelayer (%) PS 79.95 79.8 79 75 79.8 79.85 79.9 100 70 CB 0.05 0.2 1 5 0.20.15 0.1 0 10 TiO₂ 20 20 20 20 20 20 20 0 20 Film configurationfront/core/back front/core/back (ratio of layers) (3/1/3) (3/1/3)Imperviousness to light A AA AA AA AA AA A C AA (numeral in FIG. 3) (a)(b) (c) (d) Whiteness A A A B AA AA AA AA C Heat shrinkage (%) 53 53 5148 54 54 53 54 54 Appearance of contents A A A A A A A A C

TABLE 3 Comparative Example Example 14 15 16 17 5 6 Front layer (%) PET80 80 80 80 80 80 TiO₂ 20 20 20 20 20 20 Core layer (%) PET 79.95 79.879 75 100 95 CB 0.05 0.2 1 5 0 5 TiO₂ 20 20 20 20 0 0 Film configurationfront/core/back front/core/back front/core (ratio of layers) (3/1/3)(3/1/3) (3/1) Imperviousness to light A AA AA AA C AA Whiteness A A A BAA C Heat shrinkage (%) 71 69 68 67 71 69 Appearance of contents A A A AA C

TABLE 4 Example Com. Ex. 18 19 20 21 22 7 Front PS 90 90 90 90 90 90layer TiO₂ 10 10 10 10 10 10 (%) Core PS 99.5 99.0 99.0 94.5 94.0 100layer Pig- Red 0.5 — — 0.5 — — (%) ment Yellow — 1.0 — — — — Brown — —1.0 — 1.0 — White — — — 5.0 5.0 — Film configuration front/core/backfront/core/ (ratio of layers) (2/1/2) back (2/1/2) Imperviousness tolight A A A A A C (numeral in FIG. 4) (b) (c) (d) (e) (f) (a) WhitenessA AA A AA AA AA Appearance of contents A A A A A A

INDUSTRIAL APPLICABILITY

As is described above, the heat-shrinkable opaque white film accordingto the present invention prevents discoloration and deterioration ofcontents such as beverages and enables clear printing typically of adesign on a front layer. In addition, the shrink label using theheat-shrinkable opaque white film according to the present invention isvery useful as a label that gives an excellent impression of thecontents such as beverages when applied to a container and achieves goodlooking of the contents with original color without discomfort.

1. A heat-shrinkable opaque white film comprising a core layer; andwhite back and front layers, the core layer having a chromatic colorwith low transparency to light at wavelengths of 380 to 500 nm or anachromatic color.
 2. The heat-shrinkable opaque white film according toclaim 1, wherein the core layer contains at least one selected from thegroup consisting of black, yellow, red, and brown pigments.
 3. Theheat-shrinkable opaque white film according to one of claims 1 or 2,wherein the film has a transmission factor to light at wavelengths of380 to 500 nm of 5% or less.
 4. The heat-shrinkable opaque white filmaccording to one of claims 1 or 2, wherein the core layer has anachromatic color and wherein the film has a transmission factor to lightat wavelengths of 200 to 600 nm of 3% or less.
 5. The heat-shrinkableopaque white film according to claim 1, wherein the film has a W-valueof 60% or more on a surface of the front layer.
 6. The heat-shrinkableopaque white film according to claim 1, wherein the film has beenprepared by co-extruding back and front layers with a core layer anddrawing the coextrudate.
 7. A shrink label comprising theheat-shrinkable opaque white film of claim 1; and a preprinted ink labellayer arranged on or above a surface of the front layer of the film. 8.A labeled container body; and the shrink label of claim 7 arranged on orabove the container body.